388

CYANATES.

of which is covered from time to time, while in use, with the crocus cf iron, called alsoeolcothar of vitriol.

The polisher requires to run at a speed much short of that of the stone, or the glazer.Whatever may be its diameter, the surface must not move at a rate exceeding 70 or 80feet in a second.

CYANATES; saline compounds of cyanic acid with the bases potash, soda, ammonia,baryta, &c. The first is prepared by calcining, at a dull red heat, a mixture of ferro-cyanide of potassium (prussiate of potash) and black oxyde of manganese. The cyanateshave not hitherto been applied to any use in the arts.

CYANHYDRIC Acid ; another name for the hydrocyanic or prussic acid. See Prus-sian Blub and Pnussic Acid.

CYANIDES ; compounds of cyanogen with the metals; as cyanide of potassium, so-dium, barium, calcium, iron, mercury. The last is the only one of importance in amanufacturing point of view, since from it prussic acid is made.

CYANIDES , FERRO . Double compounds of cyanogen with iron, and of cyanogenwith another metal, such as potassium, sodium, barium, &c. The ordinary yellow prus-siate of potash has this constitution, and is called the ferro-cyanide.

CYANOGEN . A gaseous compound of two prime equivalents of charcoal = 12, andone of azote = 14 = 26; hydrogen being the radix, or 1. It consists of two volumesof vapor of carbon, and one volume of azote, condensed into one volume; and has there-fore a density equal to the sum of the weights of these three gaseous volumes = 1'815-Cyanogen is readily procured by exposing the cyanide of mercury to a dull red heat ina retort; the gas is evolved and may be collected over mercury. Its smell is very sharp

and penetrating; it perceptibly reddens tincture of litmus; it is condensable by pressureat a low temperature into a liquid ; and by a still greater degree of cold, it is solidified-When a lighted taper is applied to a mixture of cyanogen and oxygen, an explosion takesplace; carbonic acid is formed, and the azote is set at liberty.

For a connected view of the various compounds of cyanogen employed in the arts, seePrussian Blue .

CIDER ( Cidre , Fr.; Jlpfelwcin, Germ.); the vinous fermented juice of the apple-The ancients were acquainted with cider and perry, as we learn from the following p as "sage of Pliny the naturalist: “Wine is made from the Syrian pod, from pears and appl esof every kind.” Book xiv. chap. 19. The term cider or cidre in French, at first writtensidre, is derived from the Latin word sicera, which denoted all other fermented liquor®except grape wine. Cider seems to have been brought into Normandy by the Moors otBiscay, who had preserved the use of it after coming into that country from Africa- 1was afterwards spread through some other provinces of France , whence it was intro-duced into England, Germany , and Russia . It is supposed that the first growths of B® r 'mandy afford still the best specimens of cider. Devonshire and Herefordshire a re * iecounties of England most famous for this beverage.

Strong and somewhat elevated ground, rather dry, and not exposed to the air of tl‘ esea, or to high winds, are the best situations for the growth of the eider apple- Thefruit should be gathered in dry weather. The juice of apples is composed of adeal of water; a little sugar analogous to that of the grape ; a matter capable of causu'j?fermentation with contact of air; a pretty large proportion of mucilage, with malic » cl ■acetic acid, and an azolized matter in a very small quantity. The seeds contain a y l1substance and a little essential oil; the pure parenchyma or cellular membrane constitunot more than two per cent, of the whole. After the apples are gathered, they arein the barn-loft for fifteen days or upwards to mellow; some of them in this case, h ^ever, become soft and brown. This degree of maturation, diminishes their mudand develops alcohol and carbonic acid; in consequence of which the cider suiteinjury. There is always, however, a little loss; and if this ripening goes a little lur ^it is very apt to do harm, notwithstanding the vulgar prejudice of the country peopthe contrary. Too much care, indeed, cannot be taken to separate the sound t0

spoiled apples ; for the latter merely furnish an acid leaven, give a disagreeable taothe juice, and hinder the cider from fining, by leaving in it a certain portion o ^parenchyma, which the gelatinous matter or the fermentation has diffused t ! ir0U A c jia-Unripe apples should be separated from the ripe also, for they possess too little srum to be properly susceptible of the vinous fermentation. _ e( j by

In France , where cider making is most scientifically practised, it is P re P c i—crushing the apples in a mill with revolving edge-stones, turned in a circular s , ve iglittern by one or two horses. When the fruit is half mashed, about one fifth of i gxp e “of river water is added, or the water of lakes. The latter have been found oyrience to be preferable to other water. rtllel 1°

In some places a mill composed of two cast-iron fluted cylinders placed P ar Q lie ofeach other under the bottom of a hopper, is employed for crushing the apple®- ^ teC .the cylinders is turned by a winch, and communicates its motion in the opP°-